LeetCode: Combination Sum II

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.

Each number in C may only be used once in the combination.

Note:

• All numbers (including target) will be positive integers.
• Elements in a combination (a₁, a₂, … , a_k) must be in non-descending order. (ie, a₁ ≤ a₂ ≤ … ≤ a_k).
• The solution set must not contain duplicate combinations.

For example, given candidate set 10,1,2,7,6,1,5 and target 8, 
A solution set is: 
[1, 7] 
[1, 2, 5] 
[2, 6] 
[1, 1, 6] 

class Solution {
public:
    void comb(vector<int> &num, vector<int> &count, vector< vector<int> > &result, 
    vector<int> &record, int target, int sum, int pos, int s)
    {
        if (sum == target)
        {
            result.push_back(vector<int>());
            for (int i = 0; i < pos; ++i)
                result.back().push_back(record[i]);
        }
        
        if (pos >= record.size() || sum > target)
            return;
        
        for(int i = s; i < num.size(); ++i)  
        { 
            if (count[i] > 0)
            {
                count[i]--;
                record[pos] = num[i];
                comb(num, count, result, record, target, sum+num[i], pos+1, i); 
                count[i]++;
            }
        }
    }
    
    vector<vector<int> > combinationSum2(vector<int> &num, int target) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int nSize = num.size();
        vector< vector<int> > result;
        if (nSize == 0) return result;
        sort(num.begin(), num.end());
        vector<int> nums;
        nums.push_back(num[0]);
        vector<int> count;
        count.push_back(1);
        for(int i = 1; i < num.size(); ++i)
        {
            if (num[i] == nums.back())
                ++count.back();
            else
            {
                nums.push_back(num[i]);
                count.push_back(1);
            }
        }
        vector<int> record(nSize);
        comb(nums, count, result, record, target, 0, 0, 0);
        return result;
    }
};